Every so often when the plane is full, there can be a "normal" person sat in the middle seat when the PM gets on. There is normally a seat swap with the DPS person getting the middle seat and the "normal" person taking the aisle seat. I've then often seen them talk.
Similar the flight after the election, lots of people came up to congratulate him on the election win.
When he has got off flights I've seen him pose for photos, talk to people, etc. too.